Register Descriptions
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SPRUH22I – April 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
External Peripheral Interface (EPI)
Table 17-18. EPI Host-Bus 8 Configuration (EPIHB8CFG) Register Field Descriptions (continued)
Bit
Field
Value
Description
7-6
WRWS
Write Wait States
This field adds wait states to the data phase of CS0 (the address phase is not affected). The effect
is to delay the rising edge of WR (or the falling edge of WR). Each wait state adds 2 EPI clock
cycles to the access time. The WRWSM bit in the EPIHB8TIME register can decrease the number
of wait states by 1 EPI clock cycle for greater granularity. This field is not applicable in BURST
mode.
0x0
Active WR is 2 EPI clocks
0x1
Active WR is 4 EPI clocks
0x2
Active WR is 6 EPI clocks
0x3
Active WR is 8 EPI clocks
This field is used in conjunction with the EPIBAUD register.
5-4
RDWS
Read Wait States
This field adds wait states to the data phase (the address phase is not affected).
The effect is to delay the rising edge of RD/Oen (or the falling edge of RD). Each wait state adds
two EPI clock cycles to the access time. The RDWSM bit in the EPIHB8TIME register can decrease
the number of wait states by 1 EPI clock cycle for greater granularity. This field is not applicable in
BURST mode.
0x0
Active RD is 2 EPI clocks.
0x1
Active RD is 4 EPI clocks.
0x2
Active RD is 6 EPI clocks
0x3
Active RD is 8 EPI clocks
This field is used in conjunction with the EPIBAUD register
3-2
Reserved
Reserved
1-0
MODE
Host Bus Sub-Mode
This field determines which of four Host Bus 8 sub-modes to use. Sub-mode use is determined by
the connected external peripheral.
When used with multiple chip select option and the CSBAUD bit is set to 1 in the EPIHB8CFG2
register, this configuration is for CS0. If the multiple chip select option is enabled and CSBAUD is
clear, all chip-selects use the MODE encoding programmed in this register.
0x0
ADMUX – AD[7:0]
Data and Address are muxed.
0x1
ADNONMUX – D[7:0]
Data and address are separate.
0x2
Continuous Read - D[7:0]
This mode is the same as ADNONMUX, but uses address switch for multiple reads instead of OE
strobing.
0x3
XFIFO – D[7:0]
This mode adds XFIFO controls with sense of XFIFO full and XFIFO empty. This mode uses no
address or ALE.